1. Field of the Invention
The present invention relates to a reservoir tank for an automobile and, more particularly, to a reservoir tank for an automobile, which is provided with a height-adjustable sub filler neck so as to be retracted when not in use and extracted when filling coolant, whereby the reservoir tank can be disposed low in the automobile.
2. Description of Related Art
In an automobile having an internal combustion engine, generally, heat generated in the engine is transferred to a cylinder head, a piston, a valve and the like. Thus, if temperature of such components is excessively increased, the strength of the components is lowered due to thermal expansion and deterioration thereof, and the durability of the engine is reduced, and knocking or pre-ignition phenomenon occurs due to a poor combustion state and thus the engine power is reduced.
In addition, if the engine is not cooled sufficiently, an oil film formed on an internal surface of a cylinder is stopped, thereby degenerating lubrication performance. Further, engine oil is deteriorated, and thus the cylinder may be worn out abnormally. Furthermore, the piston may be bonded to the inner surface of the cylinder.
In order to cool the engine, the automobile is typically provided with a water-cooled cooling apparatus.
The water-cooled cooling apparatus functions to lower temperature of the cylinder block and the cylinder head, while the coolant is circulated therethrough by a water pump. The water-cooled cooling apparatus includes a radiator for radiating heat of the coolant, a cooling fan and a thermostat.
Meanwhile, a reservoir tank 10 forming a cooling module together with a condenser, a radiator 1 and a fan and shroud assembly is provided at a carrier. This is called as a front end module.
FIG. 1 is a perspective view of a conventional reservoir tank 10, and FIG. 2 is a cross-sectional view of the conventional reservoir tank 10.
Referring to FIG. 1, the radiator 1 functions to cool the coolant of which temperature is increased while being passed through an engine. The radiator 1 basically includes an upper/lower tank assembly 2, 2′, and a radiator core 3 having a tube 3a and a fin 3b interposed between the fins 3b. 
The upper/lower tank assembly 2, 2′ may be formed by a header 2a which is coupled with the tube 3a of the radiator core 3, and a tank 2b which encloses the header 2a so as to form a passage.
Meanwhile, internal pressure of the radiator 1 may be excessively increased due to change in temperature and volume of the radiator 1 while the coolant is flowed therein. Also there may be not sufficient coolant in the radiator 1.
In order to solve the above-mentioned problems, the radiator 1 is communicated with the reservoir tank 10 (subsidiary tank) such that the coolant in the radiator 1 is discharged to the reservoir tank 10 when the internal pressure of the radiator 1 is excessively increased, and the coolant is supplied to the radiator 1 when the internal pressure or temperature is lowered.
The reservoir tank 10 is formed with a filler neck 4. In general, an overflow pipe 4a is formed at the side of the filler neck 4 and connected with the radiator 1.
At the filler neck 4, there is provided a radiator cap which has a pressure vale for closing an opened portion.
More detailedly, referring to FIG. 2, an upper tank 11 and a lower tank 12 of which a lower portion and an upper portion faced to each other are opened are coupled with each other so as to form a coolant storing portion 13.
A coolant discharging port 11a is formed at a side of the upper tank 11 so as to discharge the coolant to an outside when the coolant stored in the reservoir tank 10 is over a desired amount, and a filler neck 11b for injecting the coolant is formed at an upper side of the upper tank 11 so as to be protruded more than an upper surface thereof.
The coolant discharging port 11a is connected with a drain hose 11c, and the filler neck 11b is closed by a detachable cap 14. A cap sealing portion 14a is provided at an inner surface of the cap 14 so as to be closely contacted with the filler neck 11b, thereby preventing the coolant from being leaked.
A coolant inlet port 12a is provided at a side of the lower tank 12 and connected with the overflow pipe 4a (referring to FIG. 1) of the filler neck 4.
However, in the conventional reservoir tank for an automobile, the filler neck 11b is integrally formed with the reservoir tank 10. If the filler neck 11b has a too low height, it is not facile to inject the coolant due to a narrow space. But if the filler neck 11b has a too high height to enhance user's convenience, it requires many spaces in an engine room, and thus there is a problem in layout.
Moreover, if the filler neck 11b has a too low height, it may cause increased injuries to an accident victim when a car accident occurs.
Recently, there has been proposed a method in which the reservoir tank is disposed at the fan and shroud assembly in order to increase space efficiency in the engine room and also to improve productivity.
However, in case that the reservoir tank is disposed at the shroud assembly, the cooling module is installed in the carrier, and the reservoir tank is thus moved to the side of the carrier. Therefore, it is difficult by an upper member of the carrier to secure a space for forming the filler neck, and also since a distance from the filler neck is spaced apart due to a height of the upper member, it is further difficult to inject the coolant.